Tinkering not finished; McKenzie waived

An NFL roster is as fluid as a Mountain Dew or a Heineken, the only stable thing being its limit of 53 players.

Players come, and they go. All the time.

The Patriots released 20 players Saturday to get down to the league-mandated roster limit. They began the never-ending process of tinkering with their personnel yesterday, cutting linebacker Tyrone McKenzie and claiming tackle Steve Maneri off waivers.

McKenzie’s release comes as a surprise, seeing as how he was a third-round draft choice (97th overall) just two years ago.

However, it does appear the Patriots are willing to cut their losses faster these days as opposed to in the past when a high-draft pick like Chad Jackson (second round, 2006) could participate in three training camps and show very little in the way of improvement before being jettisoned.

McKenzie started camp with a bang, drilling running back Laurence Maroney with a helmet-popping, pad-quaking hit during a goal-line drill on opening day.

He ended the preseason in similar fashion, making a game-high 10 tackles in the Patriots’ 20-17 loss to the New York Giants on Thursday.

But in between, McKenzie didn’t show much on the practice field, although he did show up for work every day. That was no small feat for a player who basically missed all of his rookie season after suffering a major knee injury in April 2009.

“I just keep coming out here and working hard,” McKenzie said last week. “I’m trying to improve every day. The coaches will see if you’ve improved and I feel that I’ve improved, but you just have to keep working hard.”

The coaches apparently didn’t see enough improvement. Or McKenzie might have been caught in a numbers game.

The Patriots have depth issues at numerous positions on defense, but inside linebacker isn’t one of them due to the presence of third-year pros Jerod Mayo and Gary Guyton and promising rookies Brandon Spikes and Dane Fletcher. It wouldn’t be surprising if the Patriots brought McKenzie back down the road — if he doesn’t land a job somewhere else first.

Maneri is a rookie from Temple who played tight end in college, but had shifted to left tackle after going undrafted and signing with the Texans. The 6-foot-7, 290-pounder is obviously a long-term project, but with that kind of size and versatility is worth at least a short look from the Patriots.